We evaluated the effects on pulmonary and cardiovascular functions of treatment for freshwater near-drowning with continuous positive pressure ventilation (CPPV) and determined whether oxygen delivery (Do2) is improved by the administration of dopamine or iv fluids. Fifteen anesthetized dogs aspirated distilled water, 22 ml/kg. All variables were measured before and at 15-min intervals after aspiration. Intrapulmonary shunting (Qsp/Qt) increased from 0.08 ± 0.07 to 0.64 ± 0.15, while the cardiac output (CO) decreased from 4.2 ± 1.3 to 3.2 ± 1.2 L/min 15 min after near-drowning. Heart rate (HR), mean arterial blood pressure (MAP), pHa, Pao2, and Do2 decreased and CVP and pulmonary artery pressure (MPAP) increased. With controlled mechanical ventilation (CMV) and an Fio2 of 0.4, Qsp/Qt decreased to 0.40 ± 0.17. However, the CO and Do2 also decreased. With CMV and 15 cm H2O of PEEP, Qsp/Qt returned to the baseline value but CO decreased to 1.3 ± 0.5 L/min. The MAP and Do2 decreased further and systemic vascular resistance (SVR), CVP, MPAP, pulmonary artery wedge (occlusion) pressure (WP), Pao2, and arteriovenous oxygen content difference (C[a-v]O2) increased. Then the dogs were divided into 3 groups and treated as follows: no changes in therapy (group 1), iv infusion of dopamine at a rate of 15 μg/kg.min (group 2), or 2 consecutive infusions (625 ± 61 and 369 ± 76 ml) of lactated Ringer's solution (group 3). Thirty min later, group 1 had an increased HR and pulmonary vascular resistance (PVR). In group 2, HR increased and CVP decreased. In group 3, CO, MAP, CVP, WP, and Do2 increased and SVR, PVR, and C(a-v)o2 decreased. We conclude that CMV with PEEP markedly decreases Qsp/Qt after freshwater near-drowning and the administration of iv fluids can return cardiovascular function toward baseline without adversely affecting Qsp/Qt; thus, Do2 is improved.
